Geotechnical Engineering - II

The consolidation process is most significant in which type of soil?

Which of the following is common test used to determine the consolidation properties of soil?

The Mohr-Coulomb failure criterion is used to describe-

What effect does an increase in moisture have on the shear strength of clay soils?

The most common type of slope failure is-

Which of the following conditions is likely to lead to increased slope instability?

What the importance of determining the groundwater level during soil exploration?

Geophysical methods in soil exploration include-

Which of the following is NOT typically a part of a soil exploration report?

Which of the following is NOT a method to calculate earth pressure?

What do you mean by soil consolidation? Also enlist primary factors affecting soil consolidation?

For a soil undergoing consolidation. Initial void ratio = 0.7; Final void ratio = 0.5; Thickness of the clay layer = 5m; Specific weight of water = 9.81 kN/m³. Calculate: (i) The change in void ratio (ii) The primary consolidation settlement

What is shear strength of soil and write down the factors affecting the shear strength of soil and their significance in geotechnical engineering.

A tri-axial test is conducted on a saturated clay sample. The following data is obtained: Cell pressure = 100 kPa and Deviator stress at failure = 250 kPa. Calculate: (i) The effective normal stress at failure. (ii) The shear strength parameters cohesion and angle of internal friction assuming a linear Mohr-Coulomb failure envelope.

What are the main factors affecting slope stability? Also explain the role of shear strength in slope stability?

A slope of height 12 m has a unit weight of soil of 18 kN/m³, cohesion of 15 kPa, and an internal friction angle of 28 degrees. An external load is applied at the top of the slope. Calculate the factor of safety.

What methods are commonly used in soil exploration? Also explain what are the factors that influence the choice of soil exploration methods? Describe common testing methods.

A soil layer is located at a depth of 5 m with a total stress of 100 kPa. The groundwater table is at 2 m depth, and the unit weight of the soil is 18 kN/m³. Calculate the effective stress at the depth of 5 m.

Discuss the significance of consolidation in geotechnical engineering and its practical applications.

A saturated clay layer has a thickness 4m and a coefficient of consolidation $ (C_v) $ of $ 1 \times 10^{-5} \text{ m}^2/\text{s} $. A load of 100 kPa is applied on top of this layer. Assuming one-dimensional conditions, estimate the time required for 50% consolidation.

Explain how laboratory tests are used to determine the shear strength of soil and describe the methods used for slope stability analysis.

A direct shear test is performed on a sandy soil sample. The following data are recorded: Normal stress applied = 150 kPa, Shear force at failure = 90 kN, Area of the shear box = 0.6 m². Calculate: 1. The shear stress at failure. 2. The effective stress if the pore water pressure at failure is 20 kPa. 3. The cohesion and angle of internal friction using the Mohr-Coulomb failure criterion.

Describe the methods used for slope stability analysis and explain the wedge failure Swedish circle method in detail.

A slope of height H = 10 m consists of saturated clay with the following properties: Cohesion = 25 kPa, Angle of internal friction = 15°. Assume the slope is inclined at an angle $ \beta = 30^{\circ} $. Calculate the Factor of Safety (FOS) using the limit equilibrium method. For simplicity, assume a planar failure surface.

What is the purpose of soil instrumentation? Also enlist instruments that are commonly used in soil mechanics?

Write short notes on any two of the following:

The consolidation process is most significant in which type of soil?

Which of the following is common test used to determine the consolidation properties of soil?

The Mohr-Coulomb failure criterion is used to describe-

What effect does an increase in moisture have on the shear strength of clay soils?

The most common type of slope failure is-

Which of the following conditions is likely to lead to increased slope instability?

What the importance of determining the groundwater level during soil exploration?

Geophysical methods in soil exploration include-

Which of the following is NOT typically a part of a soil exploration report?

Which of the following is NOT a method to calculate earth pressure?

What do you mean by soil consolidation? Also enlist primary factors affecting soil consolidation?

For a soil undergoing consolidation. Initial void ratio = 0.7; Final void ratio = 0.5; Thickness of the clay layer = 5m; Specific weight of water = 9.81 kN/m³. Calculate: (i) The change in void ratio (ii) The primary consolidation settlement

What is shear strength of soil and write down the factors affecting the shear strength of soil and their significance in geotechnical engineering.

A tri-axial test is conducted on a saturated clay sample. The following data is obtained: Cell pressure = 100 kPa and Deviator stress at failure = 250 kPa. Calculate: (i) The effective normal stress at failure. (ii) The shear strength parameters cohesion and angle of internal friction assuming a linear Mohr-Coulomb failure envelope.

What are the main factors affecting slope stability? Also explain the role of shear strength in slope stability?

A slope of height 12 m has a unit weight of soil of 18 kN/m³, cohesion of 15 kPa, and an internal friction angle of 28 degrees. An external load is applied at the top of the slope. Calculate the factor of safety.

What methods are commonly used in soil exploration? Also explain what are the factors that influence the choice of soil exploration methods? Describe common testing methods.

A soil layer is located at a depth of 5 m with a total stress of 100 kPa. The groundwater table is at 2 m depth, and the unit weight of the soil is 18 kN/m³. Calculate the effective stress at the depth of 5 m.

Discuss the significance of consolidation in geotechnical engineering and its practical applications.

A saturated clay layer has a thickness 4m and a coefficient of consolidation $ (C_v) $ of $ 1 \times 10^{-5} \text{ m}^2/\text{s} $. A load of 100 kPa is applied on top of this layer. Assuming one-dimensional conditions, estimate the time required for 50% consolidation.

Explain how laboratory tests are used to determine the shear strength of soil and describe the methods used for slope stability analysis.

A direct shear test is performed on a sandy soil sample. The following data are recorded: Normal stress applied = 150 kPa, Shear force at failure = 90 kN, Area of the shear box = 0.6 m². Calculate: 1. The shear stress at failure. 2. The effective stress if the pore water pressure at failure is 20 kPa. 3. The cohesion and angle of internal friction using the Mohr-Coulomb failure criterion.

Describe the methods used for slope stability analysis and explain the wedge failure Swedish circle method in detail.

A slope of height H = 10 m consists of saturated clay with the following properties: Cohesion = 25 kPa, Angle of internal friction = 15°. Assume the slope is inclined at an angle $ \beta = 30^{\circ} $. Calculate the Factor of Safety (FOS) using the limit equilibrium method. For simplicity, assume a planar failure surface.

What is the purpose of soil instrumentation? Also enlist instruments that are commonly used in soil mechanics?

Write short notes on any two of the following:

The compressibility of clays may also be caused by the following factor.

Bishop's simplified method of slices satisfies

Identify the incorrect statement. The stability of a slope is decreased by

For saturated, normally consolidated soils, skempton's pore pressure coefficients can be represented as

In an Undrained triaxial compression test, the sample failed at a deviator stress of 200 kN/m² when the cell pressure was 100 kN/m². The cohesion intercept is

For an undisturbed sample, the area ratio of the samples should be

If the actual value of the standard penetration number (N) is greater than 15 for fine sands below water table, the corrected value of N is

Taylor's stability number curves are used for the analysis of stability of slopes. The angle of shearing resistance used in the chart is the

After the hydrostatic pressure is reduced to zero, some compression of soil takes place by the process of

The Area Ratio for the soil sampler used for soil exploration is given by:

Explain the Friction circle method for the analysis of stability of finite slopes.

A granular soil having saturated unit weight = 19 kN/m³ and angle of internal frictional resistance = 35°. A slope has to be made of this granular soil. Determine the safe angle of slope considering the factor of safety = 1.3 if: (i) The soil slope is dry without seepage (ii) The seepage occurs parallel to the soil slope with the water table at a depth of 1.5 m from ground level.

Define consolidation. Explain different types of consolidation.

What are the assumptions of Terzaghi's consolidation theory? Derive the Terzaghi's One-dimensional consolidation equation.

What are the causes of sample disturbance? How are they taken care of in samples for undisturbed sampling?

A direct shear test is run on medium sand under the normal stress of 50 kPa. The maximum shear stress at failure is measured as 30 kPa. Draw the Mohr's circle at failure, and determine the magnitude of the principle stresses in the failure zone. What is the orientation to the plane of maximum shear stress at failure.

Explain the conditions when vane shear test is suitable for determining the shear strength of the soil. Derive an expression for shear strength of soil in terms of applied torque and vane dimensions considering shearing at top, bottom and surrounding soil. An in situ vane shear test was conducted in a clay soil at the bottom of a borehole. A torque of 150 N-m was required to shear the soil. What was the undrained shear strength of clay neglecting shearing resistance at the top? The vane was 100 mm in diameter and 150 mm long.

In the laboratory test on a clay sample, of thickness 25 mm drained at top only, 50% consolidation occurred in 11 minutes. Find the time required for the corresponding clay layer in the field, 2 m thick and drained at top and bottom to undergo 70% consolidation. Assume $ T_{50} = 0.197 $, $ T_{70} = 0.405 $.

A sample of dry cohesionless soil whose angle of internal friction is 35°, is subjected to a triaxial test. If the minor principal stress $ (\sigma_3) $ is 105 kPa, at what values of deviator stress $ (\Delta\sigma) $ and major principal stress $ (\sigma_1) $ will the test specimen fail?

Explain Swedish circle method for analysis of stability of finite slope.

What is coefficient of consolidation of soil? What are the methods to determine coefficient of consolidation. Describe any one.

Describe the salient features of a good sub-soil investigation report.

The compressibility of clays may also be caused by the following factor.

Bishop's simplified method of slices satisfies

Identify the incorrect statement. The stability of a slope is decreased by

For saturated, normally consolidated soils, skempton's pore pressure coefficients can be represented as

In an Undrained triaxial compression test, the sample failed at a deviator stress of 200 kN/m² when the cell pressure was 100 kN/m². The cohesion intercept is

For an undisturbed sample, the area ratio of the samples should be

If the actual value of the standard penetration number (N) is greater than 15 for fine sands below water table, the corrected value of N is

Taylor's stability number curves are used for the analysis of stability of slopes. The angle of shearing resistance used in the chart is the

After the hydrostatic pressure is reduced to zero, some compression of soil takes place by the process of

The Area Ratio for the soil sampler used for soil exploration is given by:

Explain the Friction circle method for the analysis of stability of finite slopes.

A granular soil having saturated unit weight = 19 kN/m³ and angle of internal frictional resistance = 35°. A slope has to be made of this granular soil. Determine the safe angle of slope considering the factor of safety = 1.3 if: (i) The soil slope is dry without seepage (ii) The seepage occurs parallel to the soil slope with the water table at a depth of 1.5 m from ground level.

Define consolidation. Explain different types of consolidation.

What are the assumptions of Terzaghi's consolidation theory? Derive the Terzaghi's One-dimensional consolidation equation.

What are the causes of sample disturbance? How are they taken care of in samples for undisturbed sampling?

A direct shear test is run on medium sand under the normal stress of 50 kPa. The maximum shear stress at failure is measured as 30 kPa. Draw the Mohr's circle at failure, and determine the magnitude of the principle stresses in the failure zone. What is the orientation to the plane of maximum shear stress at failure.

Explain the conditions when vane shear test is suitable for determining the shear strength of the soil. Derive an expression for shear strength of soil in terms of applied torque and vane dimensions considering shearing at top, bottom and surrounding soil. An in situ vane shear test was conducted in a clay soil at the bottom of a borehole. A torque of 150 N-m was required to shear the soil. What was the undrained shear strength of clay neglecting shearing resistance at the top? The vane was 100 mm in diameter and 150 mm long.

In the laboratory test on a clay sample, of thickness 25 mm drained at top only, 50% consolidation occurred in 11 minutes. Find the time required for the corresponding clay layer in the field, 2 m thick and drained at top and bottom to undergo 70% consolidation. Assume $T_{50} = 0.197$, $ T_{70} = 0.405 $.

A sample of dry cohesionless soil whose angle of internal friction is 35°, is subjected to a triaxial test. If the minor principal stress $(\sigma_3)$ is 105 kPa, at what values of deviator stress $(\Delta\sigma)$ and major principal stress $(\sigma_1)$ will the test specimen fail?

Explain Swedish circle method for analysis of stability of finite slope.

What is coefficient of consolidation of soil? What are the methods to determine coefficient of consolidation. Describe any one.

Describe the salient features of a good sub-soil investigation report.

• Wash boring
• Split-spoon samplers (with neat sketches)
• Static-cone penetration test
• Taylor stability number
• Effective shear strength parameters
• Pre-consolidated and under consolidated soils